Measurement of carotid body blood flow in cats by use of radioactive microspheres

To resolve the controversy regarding carotid body blood flow, we used the radioactive microsphere technique for determination of tissue blood flow. We also measured the blood flow to several other tissues in the cat. Blood flow experiments were performed on 13 cats that were anesthetized, paralyzed, and mechanically ventilated with air. Different numbers of differently labeled 9-, 15-, and 25-micron microspheres were injected via a catheter into the left atrium. It was determined that one injection of 5 x 10(6) 15-micron microspheres was appropriate for the determination of carotid body blood flow. Flows to the carotid bodies and other organs by use of this protocol were as follows (ml.min-1.100 g-1, means +/- SE): carotid bodies, 1,417 +/- 143; adrenal glands, 406 +/- 89; left kidney, 355 +/- 69; right kidney, 375 +/- 74; heart, 201 +/- 39; liver 81 +/- 14; pancreas, 80 +/- 21; superior cervical ganglia, 62 +/- 9; carotid artery wall, 2.4 +/- 1.1. The blood flow to the carotid bodies was the highest for any organ. This measurement provides new evidence that tissue blood flow to the carotid body is very high. This high flow is consistent with the prompt physiological reflex functions of the carotid body.     

Nontraumatic aortic blood flow sensing by use of an ultrasonic esophageal probe.

The measurement of blood velocity fields, volume flow, and arterial wall motion in the descending thoracic aorta provides essential hemodynamic information for both research and clinical diagnosis. The close proximity of the esophagus to the aorta in the dog makes it possible to obtain such data nonsurgically using an ultrasonic esophageal probe; however, the accuracy of such a probe is limited if the angle between the sound beam and the flow axis, known as the Doppler angle, is not precisely known. By use of a pulsed Doppler velocity meter (PUDVM) and a triangulation procedure, accurate empirical measurement of the Doppler angle has been obtained, allowing quantification of blood velocity scans across the aorta. Volume flow is obtained by integration of blood velocity profiles and arterial wall motion is measured with an ultrasonic echo tracking device. Accuracy of the probe was substantiated by comparison with ultrasonic and electromagnetic implanted flow cuff measurements. Use of the probe in measurement of blood velocity, volume flow and arterial wall motion at various locations along the 8- and 10-cm length of the descending thoracic aorta in adult beagle dogs is detailed. The simplicity, accuracy, and nontraumatic aspect of the technique should allow increasing use of such a probe in numerous research and clinical applications.     

Activation of wheat germ acetyl CoA carboxylase by potassium and rubidium.

Wheat germ acetyl CoA carboxylase requires certain alkali cations to exhibit maximal activity. Maximal activation results when 60 mM K⁺ or Rb⁺ are included in the assay mixture, whereas only marginal activation occurs in the presence of similar concentrations of Li⁺⁺ and Na⁺⁺. Cs⁺⁺ activates, but less effectively than K⁺ or Rb⁺. Since it is also possible to activate the enzyme maximally using 20 mM potassium isocitrate, but not 20 mM sodium isocitrate, activation of the wheat germ enzyme is due to a cation effect and not to citrate anion.     

Importance of sites of tracer administration and blood sampling in relation to leucine metabolism. Practical considerations.

For the same infusion site of L-[1-14C]leucine, sampling downstream of arterial blood underestimates leucine turnover, whereas sampling of venous blood overestimates turnover. Further, the lungs release a small but consistent amount of leucine into the blood. Unlabelled leucine also is produced by the portal-drained viscera, and some is removed immediately by the liver. These sources of leucine should thus be considered in turnover calculations.     

The use of an agglutination micromethod for erythrocyte phenotyping. Importance of improved blood transfusion safety

The authors describe an easy, sensitive and inexpensive micromethod for red blood cell typing within the Rhesus, Kell and Lewis systems.     

Active transport of potassium by the Cecropia midgut; tracer kinetic theory and transport pool size.

1. Tracer influx kinetics have been analysed theoretically to determine the size of the transport pool with no assumptions regarding the transport pathway. 2. For a calculation of the size of the transport pool to be made, the following six conditions are required by the theory: tracer steady state attained, tissue steady state attained, Isc measures next flux, small magnitude and constant time-course of efflux, and correction for decay in pumping rate. 3. The size of the pool, SI, is given by the steady state influx, Finfinity, divided by the mixing-time constant, alpha. 4. Some experimental results are analysed by three different graphical methods, and it is shown that these three methods are equivalent. Specifically, alpha is equal to the reciprocal of the 75% mixing time, t75, divided by 1n 4 and is equal to the reciprocal of the lag time, X. 5. The tracer kinetic theory is applied to active potassium transport across the isolated short-circuited midgut: the transport meets the six conditions required by the theory. 6. The size of the transport pool of potassium in one midgut is calculated to be 80.5 muequiv./g wet weight under high-K steady-state conditions. A value as high as this suggests that the pool is intracellular.     

Measurement of blood flow distribution by radioactive microspheres in the laying hen (Gallus domesticus)

• 1.1. Blood flow distribution was examined in 12 normothermic laying hens by microspheres injected via the brachial artery into the root of the aortic arch above the aortic valves.
• 2.2. Double reference sampling (brachial and sciatic) accounted for uneven microsphere distribution between upper and lower body arterial flows.
• 3.3. This easily accessible injection site yielded results comparable to those attained by left atrial injections.
• 4.4. Blood flow (ml/min g tissue) was highest in the spleen (8.2); intermediate in the brain, kidneys. adrenals, liver, follicles (1.1–3.1); below 0.5 in the skin. muscle, respiratory tract and post ovulatory follicle. Hyperthermia markedly changed this order.